An ultrasonic imaging apparatus using a method for combining CMB images of the same object including a step of seeking representative contours CNT of an interface on the images to be combined IM,[I], IM[J] is disclosed. The step is intended to define interest areas IA[I], IA[J] in the vicinity of the representative contours. The method also includes analyzing the interest areas IA[I], IA[J] being intended to allocate weights W[I], W[J] to the points on the interest areas IA[I], IA[J] and to the points corresponding to the interest areas IA[I], IA[J] on the various images. The method also includes constructing a combination image IMC, a point on the combination image IMC corresponding to a point on at least one interest area IA being obtained from a weighting of the corresponding points on the images to be combined IM[I], IM[J] according to the weights W[I], W[J] allocated in the analysis step ANA.